Radio speaker



Oct. 27, 1931. A. A. KENT ET AL RADIO SPEAKER Filed Jan.' 31, 1928 2 Sheets-Sheet l Oct. 27, 1931. A. A. KENT ET AL RADIO SPEAKE R File n: 1928 2 Sheets-Sheet 2 INVENTURSi phones, lou

Patented. Oct. 27, 1931 UNITED STATES PATENT OFFICE ARTHUR ATWATER KENT, OF ABDMORE, RUSSELL T. KINGSFORD', OF WYNCOTE, PENNSYLVANIA; SAID KINGSFORD ASSIGNOR TO SAID ARTHUR ATWATER KENT RADIO SPEAKER Application filed January 31, 1928 'Serial No. 250,789.

Our invention relates to telephonic apparatus, and articularly to amplifying teled speakers or radio speakers, utilized in connection with radio receiving apparatus.

In accordance with our invention, a sound reproducing diaphragm of relatively large area, and more articularly conical in shape, is disposed witiiin a housing or casing, the walls of which on opposite sides of the diaphragm are provided with apertures, the area of which in a wall is less than the effective area of the diaphra m, as the base area of a cone; more particu arly, the periphery of a diaphragm, particularly when entirely free and unsupported, and preferably embraced by a member, as of felt attached thereto, vibrates in proximity to but out of contact with flange structure extending along the diahragm adjacent its periphery and prefera- Bly on both sides thereof; which features of construction, singly or in combination improve the sound reproducing characteristic particularly at the lower range of audible re uencies.

ore specifically, the diaphragm is supported within the housing, preferably of metal, as by electromagnetic actuating mechanism secured to a wall thereof, with its apex directed toward said wall, the apertures through which are preferably covered or partially closed by foraminous material, as fabric or the like, and with one face of the diaphragm adjacent its periphery spaced from a flange constituting an inwardly. directed rim of the housing, and preferably with its opposite face adjacent its periphery spaced from a flanged member engaging, supported by and spaced from the first flange, and which more particularly is provided with grille structure or constitutes a part of the second apertured wall.

Our invention further resides in features of construction, arrangement and combination hereinafter described and claimed.

For an understanding of one of the forms of our invention, reference is to be had to the accompanying drawings in which:

Fig. 1 is an elevational view of a device embodying our invention.

Fig. 2 is a side elevational view in section taken on line 22 of Fig. 1.

Fig. 3 is a plan elevational view in Section taken on line 3-3 of Fig. 1.

Fig. 4 is a detailed view, on an enlarged scale, showing the disposition of the rim of a conical diaphragm utilized in my loud speaking device.

Fig. 5 is a detailed view in plan, on an enlarged scale, of electromagnetic apparatus employed in the device.

Fig. ,6 is a detail view taken on line 6-6 of Fig. 5 and disclosing the mode of mounting the speaker diaphragm on the electromagnetic driving mechanism.

Fig. 7 is a detailed view taken on line 7-7 of Fig. 6.

Referring to the drawings, the base member 1 is a casting, preferably hollow, of suitable composition, as iron, and mass provided with soft or resilient pads 2, as of felt, suitably affixed as by adhesive to its lower surface. The top'face or edge of the base memher is shaped to conform with the outline of a portion of a casing or housing member 3,.

preferably of sheet metal, as steel, and is suitably secured thereto as by bolts 4 which pass into the interior of the housing and on which are threaded nuts 5 firmly to clamp the housing and base members. The casing or housing member 3 is a relatively shallow tubular member of large diameter and preferably cylindrical,particularly when utilized with a diaphragm of the configuration hereinafter described. The left, open end of the housing, as viewed in Fig. 2, and referred to as the front of the device is provided with an inwardly directed, curved flange '6 having a shoulder portion 7 of slightly smaller diameter than. and adjacent the main body of the housing. Through the opposite or rear face 3a of the housing are apertures 8, preferably circular and of substantial diameter, and having inwardly turnedflanges 9 pressed from the sheet comprising the housing. Across each of the apertures is stretched fabric 10, or equivalent, of suitably fine mesh, maintained in position by a ring 11, as of fiber, or rubber, clamping the portion of the fabric extending beyond the periphery of the aperture firmly into contact with the outside of the flange 9.

Within a centrally disposed recessed portion 12 of the rear face of the housing is positioned electromagnetic driving mechanism 13 secured thereto as by bolts 14, 14 extending to the-exterior ofthe housing to threadably engage cap nuts 15, 15.

The electromagnetic mechanism is of the character described and claimed in co-pending Kingsford application Serial No. 155,158, filed December 16, 1926, and comprises a pair of permanently magnetized yokes or frames 16, 16, preferably duplicate in character and each cut away or recessed interiorly thereof to define a substantiallyrectangular opening. Disposed between the yokes 16, 16 is the vibratile member reed or armature 17 on either side of which, adjacent one end thereof, is disposed a washer 18, preferably of non magnetic material, as brass or the like through which and the perforated end of'reed 17 extends a bolt 19 or the like for holding the parts in assembled relation. T 0 the end't-hat the yokes 16, 16 may be held'in parallel relation or substantially'so, at theend thereof removed from thevbolt 19, there is provided the spacing washer 20, preferably of non-magnetic material-as brass orthe like and whose thickness corresponds substantially with the combinedthickness of reed17 and vashers 18. Passing through this end of frames 16, 16

and Washer 20 isthe bolt .21, preferably corresponding with bolt 19.

Secured between the yolres or frames 16, 16 bythe bolts or screws 1% are theinwardly direct-ed pole pieces22 each of which is bifurcated to form the spaced pole piece extensions or end portions 23and The extensions 23 are offset in opposite directions and disposed in superposed or spaced relation for the reception of the .free end of reed 17. The pole piece extensions 2% are not offset, as are the extensions 23, butareextended in suitable close relation to .the edges of reed 1'? to thereby provide a shunt path for the magnetic flux threading through said reed by virtue of-the coil or winding associated therewith and which is traversed by fluctuating voiceor sound-representing current, sueas exists, for example, in the anode circuit of a detector or audio frequency amplifier as utilized commonly in radioreceivin circuits. The coil 25 is supported on the polepieces by members 26 directly in contact with the inner bore of the coil, orwith a strip or layer 2-7 of paper, cloth or the like interposed between. The terminals 28 and 28a of the coil are connected to binding posts and 29a mounted in spaced relation on a member or plate 30 preferably held in place on a yoke or frame 16 by the aforesaid bolt or screw 21. The plate 30 may be formed of suitable insulating material as a phenol condensation product, or hard rubber, but preferably comprises a fabric as linen, or canvas impregnated in a phenol condensation product. As hereinbefore described, the reed 17 is clamped between the yokes 16, 16 by the bolt 19. Between this screw and the coil C and preferably extending through cars 31 of yolres 16, 16 are the members or screws 32 and 35 each of which at its end engages an oppo te face of the reed 17. The screws and ll are adjustable to vary the dimensions of the air gaps between the free end of the reed '1'? and the adjacent faces of pole extensions 23.

Member 3 1 maybe secured to reed 1"? in any suitable manner, preferably, however, as illustrated by riveting a block 35 to the reed and riveting the block and member iii to each other. The diaphragm 36 preferably conical, and of China wood, parchment or the like, at its apex is provided with a circular opening faced by the headed or turned portion of a conical member 37 of suitable materialasalunnnum or soft steel, disposed exteriorly upon the diaph -agm 36. Disposed cxteriorly thereof is the conical facing member or washer 38, preferably of hard steel or the like. As shown, the inner portion of member-3T is turned or headed and encompasses theadjacent edges of the diapl'iragm 36 and member38. Resting on the exposed face of member 38 are the an gularly d' )osed portions of a supportimig member or on t 39 of steel or other rigid material Ctjl'll})l'lb..l two legs which converge to form a pociretre ceiving the end of member Passing through alignedperforations in the pocketed portion of bracket 39 and the end of member 3% 1s bolt or the lllie 10. The angular portions ofthe bracket 39 and members 31' and. 38 may be rigidly united with the diaphragm 36 by utilizing a plurality of rive's'or the like 10'eachl1eaded on opposite sides of the diaphragm.

The member 3% is of spring steel as phosphor bronze or the like, and due to its flexibility bends in a plane extending at right angles longitudinally of the yolzes 16, 16 and as a'result, due to the inertia of the cone, little or no transversebodily movement is imparted thereto due to the pivotal movement of reed 17. To prevent contact between the flexible member and the cone intern'icdiate its ends, and to dampen transverse vibration ofthe member there is provided a butler ring 34L, of rubber or the like. The cone :1 lcscribed and claimed in co-pending Kentapplication Serial No. 32,875, filed May 26, 1995 is unrestrained throughout and free to vibrate at its periphery, the driving member constituting the sole support therefor and relatively non-flexible in the direction coinciding with the grm 'itational plane of the cone to carry its weight without flexing or bending, for example,themember may be of substantially greater breadth tl an thickness.

The cone 36 and its electromagnetic actuating mechanism 13 when assembled and dis- 1 I te'ct by Letters Patent is:

= 1-. A housing for a conical sound-reproducing diaphragm of large area having a freely vibratory periphery, comprising walls posed as a unit within the housing member 3, are substantially completely enclosed thereby, the base'of the cone, however, projects slightly outside of the housing member, the periphery of the cone comprising :1 turnedback or stiffening portion 41 of diameter suitably greater than that of the opening in housing member 3 defined by flange 6.

The shoulder 7 of flange 6 is engaged by a detachable member 42 the edge of which abuts the housing approximately at its junction with the flange and is secured thereto as by screws 43. The diameter of the flange 6 at the shoulder portion 7 is reduced to permit the outer surface of the housing member 3 and that of detachable member 42 to present a single, substantially unbroken surface when assembled to form the entire or complete housing for the diaphragm 36 and its actuating mechanism.

The periphery of the diaphragm 36 secured to and preferably embraced by a member 44, of felt or equivalent vibrates freely within the region or space between the flange 6 and rim 45 of detachable member 42. The distances between adjacent faces of the flange and rim, and of the felt member 44 are sufficiently great to prevent actual contact, however slight, therebetween under all operating conditions. Within the range afforded by screws 32 and 33 for varying the position of reed 17 with respect to pole pieces 2. 23, it is not possible to adjust the position of cone 36 to effect or permit contact thereof with either the rim 45 or flange 6.

An open grille structure 46, as for example, of the character disclosed and claimed in Kingsford Design Patent No. 73,261, issued August 16, 1927, is carried by and preferably integral with the detachable structure 42 to constitute a second apertured wall of the assembled housing within which the cone 36 is completely disposed.

The features of construction described including the apertured housing member 3 and the guard ring 42 and associated grille 46, singly or in combination with each other, and particularly in combination with the flange 6 and felted edge 41 of the diaphragm improve the sound-reproducing properties of the device particularly at the lower ranges of audible frequencies.

The term free-edge or its equivalent as applied to a sound-reproducing diaphragm in the above description and appended claims, is defined as descriptive solely of a diaphragm whose periphery is to no degree in contact with and to no degree supported by any member other than the cone itself.

Further the expression diaphragm of large area as employed herein, is definitive of a diaphragm having a diameter of six inches or more, or equivalent.

What we claim as novel and desire to'proon opposite sides of said diaphragm, each having substantial area of opening therethrough in a plane parallel to the base of said conical diaphragm. I a i 2. A housing for a sound-reproducing diaphragm of large area, comprising walls on opposite sides of said diaphragm, each wall having openings therethrough whose combined area is less than the effective area of said diaphragm in a plane normal to its axis of movement.

3. A housing for a sound-reproducing diaphragm of large area, comprising walls on opposite sides of said diaphragm, each wall having openings therethrough whose combined area is less than the effective area of said diaphragm in a plane normal to its axis of movement, and structure of foraminous material partially closing the openings of at least one of said walls.

4. A housing for a conical sound-reproducing diaphragm of large area, com rising walls on opposite sides of said diapliragm, each wall having openings therethrough whose combined area is less than the base area of said conical diaphragm in a plane normal to its axis.

5. A housing for a conical sound-reproducing diaphragm of large area having a freely vibratory periphery spaced therefrom, comprising walls on opposite sides of said diaphragm, each wall having openings therethrough whose combined area is less than the base area of said conical diaphragm.

6. A housing ducing diaphragm of large area having a freely vibratory periphery spaced therefrom, comprising walls on opposite sides of said diaphragm, each wall having openings therethrough whose combined area. is less than the base area of said conical diaphragm, and structure of foraminous material partially closing the openings of at least one of said walls.

7. Housing structure for a conical soundreproducing diaphragm of large area and its actuating mechanism, comprising metal wall structure presented to the convex side of and enclosing said diaphragm, said wall structure having substantial area of opening therethrough, and a metal enclosure for said actuating mechanism projecting outwardly from said wall structure in the axis of movement of said diaphragm,

Housing tructure for a conical soundiii? reproducing diaphragm and its actuating mechanism, comprising metal wall structure presented to the convex side of and enclosing said diaphragm, and a metal enclosure for said actuating mechanism projecting outfor a conical sound-repro- 19 4 new wardl y from said wall substantially cent-rally thereof in the axis of movement of said diaphragm, said wall structure lmving a pertures circumferentially spaced about said enclo- 5 sure, the combined area of said apertures being smaller than the base. area of said conical diaphragm.

ARTHUR ATWATER KENT.

RUSSELL T. KINGSFORD; 

